Petrogenesis of some selected granitoids gneisses in Bundelkhand Craton

Bhagat, Anushil Kumar (2025) Petrogenesis of some selected granitoids gneisses in Bundelkhand Craton. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS Dissertation of Anushil Kumar Bhagat (20MS181)) 20MS181_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (3MB)

Abstract

Grey gneisses are one of the most important components of any Archean craton. These gneisses involve multiple phase of granitoids of various origin. However, most dominant component of these gneisses are the sodium-rich and potassium-poor felsic rocks, known as Tonalite-Trondhjemite-Granodiorite (TTG). These TTGs are considered as the nuclei of felsic continental crust, emerging from a world of mafic and ultramafic. Bundelkhand Craton is one of oldest cratons in the Indian shield, preserving different generations of TTGs. This study presents field, petrographic and geochemical results of five different granitoids from the north-western part of the Bundelkhand Craton, and investigates their petrogenesis and role in crustal evolution. The samples fall on the tonalite to trondhjemite field, having low Al2O3 content, K2O/Na2O ratio (0.27–1.35) and ferromagnesian content (1.89–5.40). The Rare Earth Element (REE), Sr and Y values suggest that these samples are mostly low-HREE TTGs melting at shallow crustal level, at the plagioclase stability field. This study highlights that the TTGs (from this study) of the Bundelkhand Craton are product of shallow crustal melting of low-K mafic rocks.

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